Unlike a low molecular weight light-emitting material, a polymer light-emitting material (polymeric fluorescent substance) is soluble in a solvent, and a light emitting layer in a light-emitting device can be formed by a coating method, and it has been variously studied.
For example, polyarylene type polymeric fluorescent substances are disclosed, such as, a polyfluorene (Jpn. J. Appl. Phys. volume 30, page L1941 (1991)), and a poly para-phenylene derivative (Adv. Mater. volume 4, page 36 (1992)).
As a block copolymer having fluorescence in the solid state used as a polymeric fluorescent substance, for example, JP-W-8-505167 discloses a block copolymer comprising blocks in which polythiophene are bonded not through π—π conjugated bonds, and JP-W-11-60660 discloses a block copolymer comprising blocks in which polyethylene main chains have substituents of carbazole group and blocks which have substituents containing oxadiazole groups.
JP-A-2000-159846 discloses a block copolymer which is obtained by copolymerizing a block in which monomers having hole transportation property and electron transporting property are alternatively copolymerized, with a block in which monomers having hole transportation property are polymerized. Furthermore, JP-W-8-510483 discloses a copolymer of phenylene vinylene (PPV).
However, a block copolymer in which blocks are bonded through conjugated bond has not been known.
As the above conventional manufacture method of block copolymer, there have been known are: a process which is complicated such that functional groups are introduced after polymerizing block parts, and then the functional groups are reacted with other block parts (JP-W-8-505167); and a process which seems difficult to reliably construct block portions (JP-W-11-60660, JP-W-8-510483, JP-A-2000-159846). Anyway, there has been a problem that they are complicated.
An object of the present invention is to provide a new block copolymer having fluorescence in the solid state, and the blocks are bonded through conjugated bonds, and a polymer light-emitting device (hereinafter, sometimes referred to as “polymer LED”).